scholarly journals Magnification, dust and time-delay constraints from the first resolved strongly lensed Type Ia supernova iPTF16geu

2019 ◽  
Author(s):  
S Dhawan ◽  
J Johansson ◽  
A Goobar ◽  
R Amanullah ◽  
E Mörtsell ◽  
...  
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Time Delays ◽  
Large Scale ◽  
Hubble Space Telescope ◽  
Type Ia Supernova ◽  
Model Predictions ◽  
Type Ia ◽  
Reference Images ◽  
Short Time

Abstract We report lensing magnifications, extinction, and time-delay estimates for the first resolved, multiply-imaged Type Ia supernova iPTF16geu, at z = 0.409, using Hubble Space Telescope (HST) observations in combination with supporting ground-based data. Multi-band photometry of the resolved images provides unique information about the differential dimming due to dust in the lensing galaxy. Using HST and Keck AO reference images taken after the SN faded, we obtain a total lensing magnification for iPTF16geu of $\mu = 67.8^{+2.6}_{-2.9}$, accounting for extinction in the host and lensing galaxy. As expected from the symmetry of the system, we measure very short time-delays for the three fainter images with respect to the brightest one: -0.23 ± 0.99, -1.43 ± 0.74 and 1.36 ± 1.07 days. Interestingly, we find large differences between the magnifications of the four supernova images, even after accounting for uncertainties in the extinction corrections: $\Delta m_1 = -3.88^{+0.07}_{-0.06}$, $\Delta m_2 = -2.99^{+0.09}_{-0.08}$, $\Delta m_3 = -2.19^{+0.14}_{-0.15}$ and $\Delta m_4 = -2.40^{+0.14}_{-0.12}$ mag, discrepant with model predictions suggesting similar image brightnesses. A possible explanation for the large differences is gravitational lensing by substructures, micro- or millilensing, in addition to the large scale lens causing the image separations. We find that the inferred magnification is insensitive to the assumptions about the dust properties in the host and lens galaxy.

scholarly journals Spectroscopy of the first resolved strongly lensed Type Ia supernova iPTF16geu

2020 ◽  
Author(s):  
J Johansson ◽  
A Goobar ◽  
S H Price ◽  
A Sagués Carracedo ◽  
L Della Bruna ◽  
...  
Keyword(s):  
Time Delay ◽  
Hubble Space Telescope ◽  
Signal To Noise Ratio ◽  
Spectral Energy Distribution ◽  
Compact Objects ◽  
Light Curves ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Type Ia Supernova ◽  
Type Ia

Abstract We report the results from spectroscopic observations of the multiple images of the strongly lensed Type Ia supernova (SN Ia), iPTF16geu, obtained with ground based telescopes and the Hubble Space Telescope (HST). From a single epoch of slitless spectroscopy with HST, we resolve spectra of individual lensed supernova images for the first time. This allows us to perform an independent measurement of the time-delay between the two brightest images, Δt = 1.4 ± 5.0 days, which is consistent with the time-delay measured from the light-curves. We also present measurements of narrow emission and absorption lines characterizing the interstellar medium in the SN Ia host galaxy at z = 0.4087, as well as in the foreground lensing galaxy at z = 0.2163. We detect strong Na id absorption in the host galaxy, indicating that iPTF16geu belongs to a subclass of SNe Ia displaying ”anomalously” large Na id column densities compared to dust extinction derived from light curves. For the lens galaxy, we refine the measurement of the velocity dispersion, σ = 129 ± 4 km s−1, which significantly constrains the lens model. We use ground-based spectroscopy, boosted by a factor ∼70 from lensing magnification, to study the properties of a high-z SN Ia with unprecedented signal-to-noise ratio. The spectral properties of the supernova, such as pseudo-Equivalent widths of several absorption features and velocities of the Si ii-line, indicate that iPTF16geu is a normal SN Ia. We do not detect any significant deviations of the SN spectral energy distribution from microlensing of the SN photosphere by stars and compact objects in the lensing galaxy.

scholarly journals Gravitational lens time-delay as a probe of a possible time variation of the fine-structure constant

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
L. R. Colaço ◽  
J. E. Gonzalez ◽  
R. F. L. Holanda
Keyword(s):  
Fine Structure ◽  
Time Delay ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Temporal Evolution ◽  
Structure Constant ◽  
Gravitational Lens ◽  
Fine Structure Constant ◽  
Type Ia ◽  
Ia Supernovae

AbstractA new method based on large scale structure observations is proposed to probe a possible temporal variation of the fine-structure constant ($$\alpha $$ α ). Our analyses are based on time-delay of Strong Gravitational Lensing and Type Ia Supernovae observations. By considering the runaway dilaton scenario, where the cosmological temporal evolution of the fine-structure constant is given by $$\frac{\Delta \alpha }{\alpha } \approx -\gamma \ln {(1+z)}$$ Δ α α ≈ - γ ln ( 1 + z ) , we obtain limits on the physical properties parameter of the model ($$\gamma $$ γ ) at the level $$10^{-2}$$ 10 - 2 ($$1\sigma $$ 1 σ ). Although our limits are less restrictive than those obtained by quasar spectroscopy, the approach presented here provides new bounds on the possibility of $$\frac{\Delta \alpha }{\alpha } \ne 0$$ Δ α α ≠ 0 at a different range of redshifts.

scholarly journals Lens modelling of the strongly lensed Type Ia supernova iPTF16geu

2020 ◽  
Vol 496 (3) ◽  
pp. 3270-3280
Author(s):  
E Mörtsell ◽  
J Johansson ◽  
S Dhawan ◽  
A Goobar ◽  
R Amanullah ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Host Galaxy ◽  
Total Probability ◽  
Lens Model ◽  
Density Profiles ◽  
Type Ia Supernova ◽  
Standard Candle ◽  
Type Ia ◽  
Universal Expansion

ABSTRACT In 2016, the first strongly lensed Type Ia supernova (SN Ia), iPTF16geu, at redshift z = 0.409 with four resolved images arranged symmetrically around the lens galaxy at z = 0.2163, was discovered. Here, refined observations of iPTF16geu, including the time delay between images, are used to decrease uncertainties in the lens model, including the the slope of the projected surface density of the lens galaxy, Σ ∝ r1 − η, and to constrain the universal expansion rate H0. Imaging with Hubble Space Telescope provides an upper limit on the slope η, in slight tension with the steeper density profiles indicated by imaging with Keck after iPTF16geu had faded, potentially due to dust extinction not corrected for in host galaxy imaging. Since smaller η implies larger magnifications, we take advantage of the standard candle nature of SNe Ia constraining the image magnifications, to obtain an independent constraint of the slope. We find that a smooth lens density fails to explain the iPTF16geu fluxes, regardless of the slope, and additional substructure lensing is needed. The total probability for the smooth halo model combined with star microlensing to explain the iPTF16geu image fluxes is maximized at 12 per cent for η ∼ 1.8, in excellent agreement with Keck high-spatial-resolution data, and flatter than an isothermal halo. It also agrees perfectly with independent constraints on the slope from lens velocity dispersion measurements. Combining with the observed time delays between the images, we infer a lower bound on the Hubble constant, $H_0 \gtrsim 40\, {\rm km \ s^{-1} Mpc^{-1}}$, at 68.3 per cent confidence level.

scholarly journals Hubble Space Telescope spectra of the Type Ia supernova SN 2011fe: a tail of low-density, high-velocity material with Z < Z⊙

2014 ◽  
Vol 439 (2) ◽  
pp. 1959-1979 ◽  
Author(s):  
P. A. Mazzali ◽  
M. Sullivan ◽  
S. Hachinger ◽  
R. S. Ellis ◽  
P. E. Nugent ◽  
...  
Keyword(s):  
High Velocity ◽  
Hubble Space Telescope ◽  
Low Density ◽  
Space Telescope ◽  
Type Ia Supernova ◽  
Type Ia

scholarly journals Systematic errors induced by the elliptical power-law model in galaxy-galaxy strong lens modeling

2021 ◽  
Author(s):  
Xiaoyue Cao ◽  
Ran Li ◽  
James Nightingale ◽  
Richard Massey ◽  
Andrew Robertson ◽  
...  
Keyword(s):  
Power Law ◽  
Gravitational Lensing ◽  
Time Delays ◽  
Hubble Space Telescope ◽  
Stellar Dynamics ◽  
Hubble Constant ◽  
Power Law Model ◽  
Mass Model ◽  
Mass Distributions ◽  
Model Mismatch

Abstract The elliptical power-law (EPL) mass model of the mass in a galaxy is widely used in strong gravitational lensing analyses. However, the distribution of mass in real galaxies is more complex. We quantify the biases due to this model mismatch by simulating and then analysing mock {\it Hubble Space Telescope} imaging of lenses with mass distributions inferred from SDSS-MaNGA stellar dynamics data. We find accurate recovery of source galaxy morphology, except for a slight tendency to infer sources to be more compact than their true size. The Einstein radius of the lens is also robustly recovered with 0.1\% accuracy, as is the global density slope, with 2.5\% relative systematic error, compared to the 3.4\% intrinsic dispersion. However, asymmetry in real lenses also leads to a spurious fitted `external shear' with typical strength, $\gamma_{\rm ext}=0.015$. Furthermore, time delays inferred from lens modelling without measurements of stellar dynamics are typically underestimated by $\sim$5\%. Using such measurements from a sub-sample of 37 lenses would bias measurements of the Hubble constant $H_0$ by $\sim$9\%. The next generation cosmography must use more complex lens mass models.

Cosmology from the 2dF QSO Redshift Survey

2005 ◽  
Vol 216 ◽  
pp. 95-104
Author(s):  
Scott Croom ◽  
Brian Boyle ◽  
Tom Shanks ◽  
Phil Outram ◽  
Adam Myers ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Geometric Distortion ◽  
Current Standard ◽  
Type Ia ◽  
Consistent Picture ◽  
Redshift Survey ◽  
To Come ◽  
Ia Supernovae

The 2dF QSO Redshift Survey (2QZ) is now complete and available to the astronomical community (see www.2dfquasar.org). In this paper we review some of the principle science results to come from the survey, in particular concentrating on tests for cosmological parameters. Measurements of large-scale structure using the correlation function and power spectrum, together with determinations of the geometric distortion of clustering in redshift-space have been used. These produce a consistent picture which is well matched to the now standard cosmological model with Ωm ≃ 0.3 and ΩΛ ≃ 0.7. In particular, geometric distortions provide evidence for non-zero ΩΛ independent of type Ia supernovae, the CMB, or the assumed type of dark matter (e.g. CDM). However, gravitational lensing results in the form of potential arcminute separation lensed pairs and a stronger than expected anti-correlation between QSOs and foreground galaxies in groups and clusters may prove to be inconsistent with the current standard model. These issues certainly require further investigation.

scholarly journals Pushing the Frontiers: uncovering the earliest galaxies in the Hubble Frontier Fields

2015 ◽  
Vol 11 (A29B) ◽  
pp. 812-815
Author(s):  
Rachael C. Livermore
Keyword(s):  
Gravitational Lensing ◽  
Wavelet Decomposition ◽  
Luminosity Function ◽  
Large Scale ◽  
Hubble Space Telescope ◽  
High Background ◽  
Large Scale Structures ◽  
Effective Depth ◽  
Scale Structures ◽  
Intracluster Light

AbstractWith the combination of deep Hubble Space Telescope imaging and magnification due to gravitational lensing, the Hubble Frontier Fields program offers an unprecedented opportunity to study the faint end of the luminosity function at the highest redshifts. Unfortunately, the region of the field that benefits most from this magnification (the immediate vicinity of the critical line) suffers from a high abundance of bright foreground galaxies and high background due to intracluster light. To overcome these difficulties, some method of modelling and subtracting the foreground light is required. Here, I present results using wavelet decomposition to subtract large-scale structures in the clusters, which significantly increases the effective depth of the images, and crucially opens up the most magnified regions of the clusters.

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